US 10,303,056 B2  7  8  The monomer Ma may be synthesized by reacting (meth)  acrylic acid with an iodized hydroxylactone to form a  (meth)acrylate. Examples of the monomer Ma are shown  below, but not limited thereto. Herein  RA  is as defined above.  Herein  RA  is as defined above. R$^{3 }$and R 4  each are an acid  labile group. R 5  is hydrogen, fluorine, trifluoromethyl,  cyano, or a  C$_{1 }$-C$_{6 }$ straight, branched or cyclic alkyl group.  R  $^{6 }$is a single bond or a  C$_{1 }$-C$_{6 }$ straight or branched alkylene  group in which at least one carbon atom may be substituted  by an ether or ester moiety, p is 1 or 2, and q is an integer  ofO to 4. X$^{1 }$is a single bond, a C$_{1}$-C$_{14 }$linking group which  contains an ester, ether moiety or lactone ring, a phenylene  group or a naphthylene group. X 2  is a single bond,  ----C(=0)---0- or  ----C(=O)-NH-.  Monomers Mbl and Mb2 from which the recurring units  (bl) and (b2) are derived are represented by the formulae  (Mbl) and (Mb2), respectively.  Herein  RA,  R 3  to R 6 , X1, X 2 , p and q are as defined above.  Examples of the monomer Mbl are given below, but not  limited thereto. Herein  RA  and R 3  are as defined above.  Preferably the recurring units (bl) and (b2) have the  formulae (bl) and (b2), respectively.  (bl)  (b2)  (Mbl)  (Mb2) 